Definition/General
Introduction:
Thecoma is a benign sex cord-stromal tumor composed of theca cells
Accounts for 1-2% of ovarian tumors
Produces estrogen causing hormonal effects
Contains lipid-rich spindle cells.
Origin:
Originates from ovarian stromal cells with thecal differentiation
Shows steroidogenic activity
Contains lipid-laden cells
Produces predominantly estrogen.
Classification:
Typical thecoma (90%)
Luteinized thecoma (with lutein cells)
Sclerosing thecoma (with fibrosis)
Fibrothecoma (mixed with fibroma)
Malignant thecoma (extremely rare).
Epidemiology:
Peak incidence in postmenopausal women (6th-7th decade)
Mean age 59 years
Unilateral in 95% cases
Estrogen effects in 60-70%
More common than granulosa cell tumors.
Clinical Features
Presentation:
Estrogenic effects (postmenopausal bleeding, endometrial hyperplasia)
Pelvic mass
Abdominal distension
Breast tenderness
Vaginal discharge.
Symptoms:
Postmenopausal bleeding (60-70%)
Pelvic/abdominal mass (80%)
Abdominal pain (40%)
Breast enlargement
Vulvar itching
Weight gain.
Risk Factors:
Postmenopausal age
Previous ovarian disorders
Family history (rare)
No established hormonal factors
Environmental associations unclear.
Screening:
Serum estrogen levels (elevated)
Inhibin B (elevated)
FSH/LH (suppressed)
Endometrial assessment (hyperplasia screening)
Pelvic ultrasound
Endometrial biopsy.
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Gross Description
Appearance:
Solid, well-circumscribed mass
Yellow to orange cut surface (lipid content)
Size ranges from 2-20 cm (average 8 cm)
Lobulated appearance
Soft consistency.
Characteristics:
Unilateral in 95% cases
Smooth capsule
Cut surface shows yellow-orange tissue
Lobulated pattern
Soft to firm consistency
No hemorrhage or necrosis.
Size Location:
Variable size (1-25 cm)
Average size 6-10 cm
No specific ovarian location preference
Bilateral involvement rare
Slow growth pattern.
Multifocality:
Usually unifocal
Bilateral involvement in <5%
No metastatic potential
May coexist with fibroma (fibrothecoma).
Microscopic Description
Histological Features:
Spindle to polygonal cells with lipid-rich cytoplasm
Abundant pale cytoplasm
Oval nuclei with fine chromatin
Intervening collagen
Hyalinization may be present.
Cellular Characteristics:
Plump spindle cells with abundant cytoplasm
Pale, vacuolated cytoplasm (lipid)
Oval nuclei with smooth contours
Inconspicuous nucleoli
Low mitotic activity.
Architectural Patterns:
Sheets and fascicles
Storiform pattern
Hyalinized areas
Edematous regions
Calcifications may be present.
Grading Criteria:
Benign thecoma: No significant atypia, <4 mitoses/10 HPF
Atypical thecoma: Moderate atypia
Malignant thecoma: Severe atypia, >4 mitoses/10 HPF (extremely rare).
Immunohistochemistry
Positive Markers:
Inhibin-alpha (95-100%)
Calretinin (90-95%)
SF-1 (steroidogenic factor)
Vimentin (100%)
Smooth muscle actin (focal)
CD99 (variable).
Negative Markers:
Cytokeratin (negative)
EMA (negative)
S-100 (negative)
Desmin (negative)
CD34 (negative)
Chromogranin (negative).
Diagnostic Utility:
Inhibin positivity diagnostic for sex cord-stromal tumor
Calretinin supports diagnosis
Distinguish from fibroma (inhibin negative)
SF-1 confirms steroidogenic function.
Molecular Subtypes:
Similar to other sex cord tumors
Low mutation burden
Steroidogenic gene expression
Estrogen pathway activation.
Molecular/Genetic
Genetic Mutations:
Low mutation rate
Chromosomal stability
Different from epithelial tumors
Steroidogenic pathway genes expressed.
Molecular Markers:
Inhibin overexpression
Steroidogenic enzymes (aromatase, 17β-HSD)
Estrogen receptor expression
Low Ki-67 proliferation index.
Prognostic Significance:
Excellent prognosis
Benign behavior
No malignant potential (typical cases)
Complete excision curative.
Therapeutic Targets:
Surgical excision curative
Enucleation possible
Estrogen effects resolve after removal
No hormonal therapy needed.
Differential Diagnosis
Similar Entities:
Fibroma (inhibin negative, less lipid)
Granulosa cell tumor (different morphology)
Steroid cell tumor (polygonal cells)
Luteinized thecoma
Fibrothecoma.
Distinguishing Features:
Thecoma: Lipid-rich cells
Inhibin positive
Estrogen production
Fibroma: Dense collagen
Inhibin negative
Granulosa: Coffee-bean nuclei
Call-Exner bodies
Steroid cell: Polygonal cells
Crystalloids.
Diagnostic Challenges:
Thecoma vs fibroma distinction
Fibrothecoma diagnosis
Lipid demonstration
Hormonal correlation
Sampling adequacy.
Rare Variants:
Luteinized thecoma
Sclerosing thecoma
Fibrothecoma
Thecoma with minor granulosa elements
Malignant thecoma (extremely rare).
Sample Pathology Report
Template Format
Sample Pathology Report
Complete Report: This is an example of how the final pathology report should be structured for this condition.
Specimen Information
Ovarian mass, [side], measuring [X x Y x Z] cm
Diagnosis
Thecoma
Classification
WHO Classification: Sex Cord-Stromal Tumor, Thecoma
Histological Features
Shows spindle cells with abundant pale, lipid-rich cytoplasm
Hormonal Effects
Associated with [estrogenic effects/no hormonal effects]
Special Studies
IHC: Inhibin-alpha [positive], Calretinin [positive], SF-1 [positive]
Estrogen levels: [elevated/normal]
Final Diagnosis
Ovarian Thecoma, [Side]